Preceramic resin formulations, ceramic materials comprising the preceramic resin formulations, and related articles and methods

ABSTRACT

A preceramic resin formulation comprising a polycarbosilane preceramic polymer and an organically modified silicon dioxide preceramic polymer. A ceramic material comprising a reaction product of the polycarbosilane preceramic polymer and organically modified silicon dioxide preceramic polymer is also described. Articles comprising the ceramic material are also described, as are methods of forming the preceramic resin formulation and the ceramic material.

FIELD

Embodiments of the disclosure relate generally to preceramic resinformulations that are resistant to heat and exhibit a high ceramic yieldwhen ceramified. More particularly, embodiments of the disclosure relateto preceramic resin formulations that include a polycarbosilane polymerand an organically modified silicon dioxide polymer, ceramic materialsincluding the preceramic resin formulations, articles comprising theceramic materials, and methods of forming the preceramic resinformulations and the ceramic materials.

BACKGROUND

Silicon carbide (SiC) and other ceramic materials are used to producearticles having high structural and mechanical strength at a temperatureabove 1,200° C. (2,200° F.). The articles are commonly used in aerospaceand other industries needing resistance to heat. As operationtemperatures increase above 1,200° C., material options for the articlesdecrease exponentially because metal and metal alloys are not viable.While ceramic matrix composites (CMCs) and carbon-carbon (C—C) materialsare conventionally used at these temperatures, these materials areexpensive and time intensive to produce. Processing of the CMCs and C—Cmaterials requires multiple heat treatments and processing acts todensify the materials and provide the desired strength. Producing CMCsrequires several infiltration cycles, which increases the overall costand amount of time to fabricate the CMCs. Additionally, conventionalfurnaces used to produce the articles are not sufficiently large toaccommodate large articles, such as those needed for large rocketmotors.

One method of forming SiC and other ceramic materials is from preceramicpolymers. However, conventional preceramic polymers, such aspolycarbosilanes, have a low viscosity (less than about 200 cP), whichlimits their practical use in the preparation of CMCs where thepreceramic polymer provides the matrix of the CMC. One commonly-usedpreceramic polymer is polycarbosilane. However, the polycarbosilane haslimited use due to its low viscosity and extensive cracking after curingat, for example, 121° C. (250° F.). Additionally, the ceramic materialsformed from conventional preceramic polymers exhibit high mass loss,extensive cracking at low temperature (less than about 121° C.), highporosity, and high shrinkage. Cracking of the ceramic material isworsened as high loading of fillers is needed, rendering the ceramicmaterial formed from the conventional preceramic polymers ineffective.Viscosity modifiers or cracking mitigation additives have been used withconventional preceramic polymers. However, with the modifiers oradditives, a low ceramic yield is observed at a temperature greater thanabout 816° C. (about 1500° F. Polycarbosilane has also been combinedwith a polysiloxane, such as polydimethylsiloxane, to improve itsviscosity. However, the ceramic yield of the resulting ceramic materialwas unacceptably low.

BRIEF SUMMARY

In accordance with some embodiments described herein, a preceramic resinformulation is disclosed. The preceramic resin formulation comprises apolycarbosilane preceramic polymer and an organically modified silicondioxide preceramic polymer.

In additional embodiments, a ceramic material comprising a reactionproduct of the polycarbosilane preceramic polymer and the organicallymodified silicon dioxide preceramic polymer is disclosed.

In further embodiments, a method of forming a preceramic resinformulation is disclosed and comprises combining the polycarbosilanepreceramic polymer, the organically modified silicon dioxide preceramicpolymer, and a crosslinking agent.

In yet other embodiments, a method of forming the ceramic material isdisclosed and comprises forming the preceramic resin formulation, curingthe preceramic resin formulation to form a cured preceramic resinformulation, and ceramifying the cured preceramic resin formulation toform the ceramic material.

In yet still other embodiments, an article is disclosed. The articlecomprises a reaction product of a polycarbosilane preceramic polymer andan organically modified silicon dioxide preceramic polymer, the articleconfigured as a component of a rocket motor or of a high temperatureaerostructure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified cross-sectional view of a rocket motor includingone or more ceramic material components in accordance with embodimentsof the disclosure;

FIG. 2 is a thermogravimetric analysis (TGA) curve showing the masspercent as a function of temperature for the ceramic materials describedin Example 1; and

FIG. 3 is a photograph of the ceramic materials described in Example 1.

DETAILED DESCRIPTION

A preceramic resin formulation including at least one silicon carbideprecursor and at least one silicon dioxide precursor is disclosed. Thesilicon carbide precursor and silicon dioxide precursor differ inviscosity, enabling a viscosity of the preceramic resin formulation tobe tailored by adjusting the relative amounts of the silicon carbideprecursor and silicon dioxide precursor in the preceramic resinformulation. The tailorable viscosity of the preceramic resinformulation increases the extent and nature of applications in which thepreceramic resin formulation may be used. By way of example only, theviscosity of the preceramic resin formulation may be tailored so thatthe preceramic resin formulation may be used to prepare CMCs where thepreceramic resin formulation functions as the matrix of the composite.The preceramic resin formulation may be cured (e.g., crosslinked) andceramified (e.g., pyrolyzed) to form a ceramic material. The ceramicmaterial formed from the preceramic resin formulation may be formulatedto exhibit desired material properties (e.g., rheological properties,mechanical properties, physical properties, chemical properties). Theceramic material exhibits a low mass loss, a high ceramic yield, and alow porosity when ceramified at a temperature greater than about 816° C.(greater than about 1500° F.). The ceramic material exhibits improvedperformance properties (e.g., strength) than each of the preceramicprecursors individually. The tailorable viscosity of the preceramicresin formulation may be achieved without losing ceramic yield duringthe conversion to the ceramic material. An article formed from theceramic material also exhibits reduced or no cracking. The article maybe produced by conventional composite fabrication methods, reducing thecomplexity and cost of fabricating the article.

As used herein, the term “ceramic material” means and includes areaction product of the silicon carbide precursor and silicon dioxideprecursor following cure and ceramification of the preceramic resinformulation.

As used herein, the term “ceramic yield” means and includes a residualmass of the ceramic material remaining after cure and ceramification ofthe preceramic resin formulation at a temperature of up to about 900° C.(up to about 1,652° F.).

As used herein, the term “cured preceramic resin formulation” means andincludes the preceramic resin formulation after curing and beforeceramifying.

As used herein, the term “preceramic” means and includes a polymermaterial that is converted to a ceramic material when heated to atemperature of greater than about 816° C. (greater than about 1500° F.).

As used herein, the term “preceramic resin formulation” means andincludes a formulation of the silicon carbide precursor and silicondioxide precursor before curing and ceramifying.

As used herein, the terms “comprising,” “including,” “containing,”“characterized by,” and grammatical equivalents thereof are inclusive oropen-ended terms that do not exclude additional, unrecited elements ormethod steps, but also include the more restrictive terms “consistingof” and “consisting essentially of” and grammatical equivalents thereof.

As used herein, the term “may” with respect to a material, structure,feature or method act indicates that such is contemplated for use inimplementation of an embodiment of the disclosure and such term is usedin preference to the more restrictive term “is” so as to avoid anyimplication that other, compatible materials, structures, features andmethods usable in combination therewith should or must be excluded.

As used herein, the term “configured” refers to a size, shape, materialcomposition, and arrangement of one or more of at least one structureand at least one apparatus facilitating operation of one or more of thestructure and the apparatus in a pre-determined way.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items.

As used herein, the term “substantially,” in reference to a givenparameter, property, or condition, means to a degree that one ofordinary skill in the art would understand that the given parameter,property, or condition is met with a small degree of variance, such aswithin acceptable manufacturing tolerances.

As used herein, spatially relative terms, such as “beneath,” “below,”“lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,” “left,”“right,” and the like, may be used for ease of description to describeone element's or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. Unless otherwise specified,the spatially relative terms are intended to encompass differentorientations of the materials in addition to the orientation depicted inthe figures. For example, if materials in the figures are inverted,elements described as “below” or “beneath” or “under” or “on bottom of”other elements or features would then be oriented “above” or “on top of”the other elements or features. Thus, the term “below” can encompassboth an orientation of above and below, depending on the context inwhich the term is used, which will be evident to one of ordinary skillin the art. The materials may be otherwise oriented (e.g., rotated 90degrees, inverted, flipped, etc.) and the spatially relative descriptorsused herein interpreted accordingly.

As used herein, the term “substantially” in reference to a givenparameter, property, or condition means and includes to a degree thatone of ordinary skill in the art would understand that the givenparameter, property, or condition is met with a degree of variance, suchas within acceptable manufacturing tolerances. By way of example,depending on the particular parameter, property, or condition that issubstantially met, the parameter, property, or condition may be at least90.0% met, at least 95.0% met, at least 99.0% met, or even at least99.9% met.

As used herein, the term “about” in reference to a given parameter isinclusive of the stated value and has the meaning dictated by thecontext (e.g., it includes the degree of error associated withmeasurement of the given parameter).

The following description provides specific details, such as materials,material thicknesses, and processing conditions in order to provide athorough description of embodiments of the disclosure. However, a personof ordinary skill in the art will understand that the embodiments of thedisclosure may be practiced without employing these specific details.Indeed, the embodiments of the disclosure may be practiced inconjunction with conventional fabrication techniques employed in theindustry. In addition, the description provided below does not form acomplete process flow for manufacturing the article from the preceramicresin formulation. Only those process acts and structures necessary tounderstand the embodiments of the disclosure are described in detailbelow. Additional acts to form the article from the preceramic resinformulation may be performed by conventional techniques. Also note, anydrawings accompanying the application are for illustrative purposesonly, and are thus not drawn to scale. Additionally, elements commonbetween figures may retain the same numerical designation.

The silicon carbide precursor and silicon dioxide precursor may differin viscosity from one another by at least one order of magnitude. Thesilicon carbide precursor may, for example, have a viscosity of lessthan or equal to about 250 cP at a temperature of about 25° C. while thesilicon dioxide precursor may have a viscosity of greater than or equalto about 2,500 cP at a temperature of about 25° C. While embodimentsherein describe the silicon carbide precursor as having a lowerviscosity than the silicon dioxide precursor, the silicon carbideprecursor may have a higher viscosity than the silicon dioxide precursoras long as the viscosities of the two preceramic precursors differ by atleast one order of magnitude. By selecting the viscosities of each ofthe silicon carbide precursor and silicon dioxide precursor, theviscosity of the preceramic resin formulation may be tailored asdesired.

The silicon carbide precursor is a polycarbosilane preceramic polymerformed of monomers having the following chemical structure:

where R₁ and R₂ of each monomer is independently a hydrogen (H) group, amethyl (CH₃) group, or a vinyl group (CH₂═CH) and n is an integer from 2to 10,000 (e.g., from 100 to 5,000). When vinyl groups are present, thevinyl group may be directly bonded to the silicon atom or may be bondedto the silicon atom by an alkyl group or other linker. By way of exampleonly, the alkyl group may include from one carbon atom to six carbonatoms. At least a portion of the monomers in the polycarbosilanepreceramic polymer include the vinyl group as R₁ or R₂ to enablecrosslinking with the organically modified silicon dioxide preceramicpolymer during cure of the preceramic resin formulation. The amount ofvinyl groups in the polycarbosilane preceramic polymer may be sufficientto crosslink the preceramic resin formulation. The polycarbosilanepreceramic polymer may include at least about 0.01 vinyl eq/kg, such asfrom about 0.2 vinyl eq/kg to about 5.0 vinyl eq/kg. The polycarbosilanepreceramic polymer may also include at least about 0.01 hydride eq/kg,such as from about 0.2 hydride eq/kg to about 10 hydride eq/kg. Thepolycarbosilane preceramic polymer may be photocurable, chemicallycurable, or thermally curable.

By selecting the R₁ and R₂ groups of each monomer and the degree ofpolymerization (i.e., the number of monomer repeat units), a desiredviscosity of the polycarbosilane preceramic polymer may be achieved. Thepolycarbosilane preceramic polymer is formulated to exhibit a viscosityof less than or equal to about 250 cP at a temperature of about 25° C.,such as from about 1 cP to about 250 cP at about 25° C., from about 1 cPto about 200 cP at about 25° C., from about 1 cP to about 100 cP atabout 25° C., from about 10 cP to about 250 cP at about 25° C., fromabout 10 cP to about 200 cP at about 25° C., from about 40 cP to about250 cP at about 25° C., from about 40 cP to about 200 cP at about 25°C., from about 40 cP to about 120 cP at about 25° C., from about 40 cPto about 100 cP at about 25° C., from about 5 cP to 8 cP at about 25°C., from about 4 cP to 7 cP at about 25° C., from about 8 cP to 12 cP atabout 25° C., from about 8 cP to 15 cP at about 25° C., or from about200 cP to about 250 cP at about 25° C. In some embodiments, thepolycarbosilane preceramic polymer has a viscosity of from about 40 cPto about 120 cP at about 25° C.

Such polycarbosilane preceramic polymers are commercially available fromnumerous sources including, but not limited to, EEMS, LLC (SaratogaSprings, N.Y.), Starfire Systems, Inc. (Schenectady, N.Y.), or Matech(Westlake Village, Calif.). The polycarbosilane preceramic polymer mayinclude, but is not limited to, SMP-10, StarPCS® SMP-500, or StarPCS®SMP-877 silicon carbide precursor from Starfire Systems, Inc. (Malta,N.Y.). Additional polycarbosilane preceramic polymers are commerciallyavailable from EEMS, LLC as MS 208, MS 272, MS 250, MS 440, CSO 110, orCSO 116. The polycarbosilane preceramic polymer may also include acombination of polycarbosilane preceramic polymers or a combination ofthe polycarbosilane preceramic polymer with at least one other polymer,such as a polysiloxane or other compatible polymer. The polycarbosilanepreceramic polymer may be available at a relatively low cost, such asless than about $100/pound. Commercially available polycarbosilanepreceramic polymers may also include a combination of thepolycarbosilane preceramic polymer.

The silicon dioxide precursor is an organically modified silicon dioxidepreceramic polymer formed of monomers having the following chemicalstructure:

where each of R₃ and R₄ is independently a methyl (CH₃) group or a vinylgroup (CH₂═CH) and n is an integer from 2 to 10,000 (e.g., from 100 to5,000). When vinyl groups are present, the vinyl group may be directlybonded to the silicon atom or may be bonded to the silicon atom by analkyl group or other linker. By way of example only, the alkyl group mayinclude from one carbon atom to six carbon atoms. The organicallymodified silicon dioxide preceramic polymer includes a quaternarycoordinated (QC) oxygen to silicon atom and may also be referred to as aQC silicon dioxide preceramic polymer. At least a portion of themonomers in the organically modified silicon dioxide preceramic polymermay, optionally, include the vinyl group as R₃ or R₄ to enablecrosslinking with the polycarbosilane preceramic polymer during cure ofthe preceramic resin formulation. The organically modified silicondioxide preceramic polymer may include from about 0 vinyl eq/kg to about5.0 vinyl eq/kg, such as from about 0.18 vinyl eq/kg to about 0.3 vinyleq/kg. The organically modified silicon dioxide preceramic polymer maybe photocurable, chemically curable, or thermally curable.

R₃ and R₄ of each monomer of the organically modified silicon dioxidepreceramic polymer and the degree of polymerization are selected toprovide the desired viscosity to the organically modified silicondioxide preceramic polymer. The organically modified silicon dioxidepreceramic polymer also has a low carbon content and a high degree ofquaternary coordinated oxygen to the silicon atoms in the polymer chain.The organically modified silicon dioxide preceramic polymer isformulated to exhibit a viscosity greater than about 200 cP at atemperature of about 25° C., such as greater than about 2,500 cP at atemperature of about 25° C., from about 3,000 cP to about 100,000 cP atabout 25° C., from about 4,000 cP to about 100,000 cP at about 25° C.,from about 5,000 cP to about 100,000 cP at about 25° C., from about6,000 cP to about 100,000 cP at about 25° C., from about 4,500 cP toabout 7,000 cP at about 25° C., from about 40,000 cP to about 80,000 cPat about 25° C., from about 45,000 cP to about 75,000 cP at about 25°C., from about 50,000 cP to about 70,000 cP at about 25° C., or fromabout 50,000 cP to about 60,000 cP at about 25° C. In some embodiments,the organically modified silicon dioxide preceramic polymer has aviscosity of from about 50,000 cP to about 60,000 cP at a temperature ofabout 25° C. In other embodiments, the organically modified silicondioxide preceramic polymer has a viscosity of from about 4,500 cP toabout 7,000 cP at about 25° C.

Such organically modified silicon dioxide preceramic polymers arecommercially available from numerous sources including, but not limitedto, Gelest, Inc. (Morrisville, Pa.). The organically modified silicondioxide preceramic polymer may include, but is not limited to, VQM 135,VQM 135R, VQM 146, or combinations thereof.

The preceramic resin formulation also includes a crosslinking agent,such as a radical initiator, a cationic initiator, or a hydrosilylationcatalyst. The crosslinking agent initiates crosslinking of thepolycarbosilane preceramic polymer and organically modified silicondioxide preceramic polymer by reacting the vinyl groups withsilicon-hydrogen groups in the preceramic resin formulation. The radicalinitiator may be a peroxide compound or an azo compound used to cure(e.g., crosslink) the polycarbosilane preceramic polymer and theorganically modified silicon dioxide preceramic polymer. The peroxidecompound may include, but is not limited to, benzoyl peroxide, dicumylperoxide, bis-(2,4-dichlorobenzoyl)-peroxide, or combinations thereof.The azo compound may include, but is not limited to,azobisisobutyronitrile. The cationic initiator may include a protonicacid, a Lewis acid/Friedel-Crafts catalyst (e.g., SnCl₄, AlCl₃, BF₃, andTiCl₄), carbenium ion salts (e.g. with trityl or tropylium cations), orthrough ionizing radiation. The hydrosilylation catalyst may be atransition metal catalyst, such as platinum, rhodium, ruthenium iridium,palladium, nickel, cobalt, iron, manganese, or combinations thereof. Insome embodiments, the crosslinking agent is a platinum catalyst. Thecrosslinking agent may be present at an amount sufficient to react(e.g., crosslink) the polycarbosilane preceramic polymer and organicallymodified silicon dioxide preceramic polymer and at least partiallydepends on the polycarbosilane preceramic polymer and organicallymodified silicon dioxide preceramic polymer used, as well as on thedesired cure time of the preceramic resin formulation. The crosslinkingagent may, for example, be present in the preceramic resin formulationat from about 0.01 parts per hundred parts of resin (phr) to about 2.5phr, such as from about 0.5 phr to about 2.0 phr, or about 1.0 phr.

The preceramic resin formulation may include optional components (e.g.,additives) to provide desirable properties to the ceramic materialformed from the preceramic resin formulation. If present, the additivemay be at least one compound that enhances at least one materialproperty (e.g., ceramic yield, extent of cracking) of the ceramicmaterial to be formed from the preceramic resin formulation. By way ofexample only, the additive may be a cure accelerator, an adhesionpromoter, a lubricant, a filler, a pigment, or combinations thereof.Such additives are known in the art and are not described in detailherein. In some embodiments, the preceramic resin formulation issubstantially free of additives other than the crosslinking agent. Thus,the preceramic resin formulation consists essentially of or consists ofthe polycarbosilane preceramic polymer, organically modified silicondioxide preceramic polymer, and the crosslinking agent.

The preceramic resin formulation may include from about 10% by weight(wt %) to about 90 wt % of the polycarbosilane preceramic polymer andfrom about 10 wt % to about 90 wt % of the organically modified silicondioxide preceramic polymer. The amount of each of the polycarbosilanepreceramic polymer and the organically modified silicon dioxidepreceramic polymer present in the preceramic resin formulation may beselected depending on the desired properties of the ceramic material tobe formed. In some embodiments, the preceramic resin formulationincludes 80 wt % of the polycarbosilane preceramic polymer, 20 wt % ofthe organically modified silicon dioxide preceramic polymer, and about1.0 phr of the crosslinking agent. By way of example only, thepolycarbosilane preceramic polymer is CSO-110 from EEMS, LLC and ispresent at about 100 parts, the organically modified silicon dioxidepreceramic polymer is VQM-246 from Gelest, Inc. and is present at about25 parts, and the crosslinking agent is a platinum catalyst (EEMSCLC-PL005 from Gelest, Inc.) and is present at about 1 part.

The preceramic resin formulation may be formed by mixing thepolycarbosilane preceramic polymer, the organically modified silicondioxide preceramic polymer, and the crosslinking agent, along with anyoptional additives. The polycarbosilane preceramic polymer, organicallymodified silicon dioxide preceramic polymer, and crosslinking agent maybe mixed by conventional techniques, such as by hand, using a high shearmixer, or using a planetary mixer. Mixing the components under vacuummay remove gases from the preceramic resin formulation, which inhibitsthe formation of voids or pores during curing and during the conversionof the preceramic resin formulation to the ceramic material. Thecomponents may be mixed under inert conditions, such as under argon. Thepolycarbosilane preceramic polymer, organically modified silicon dioxidepreceramic polymer, and crosslinking agent may be mixed for an amount oftime sufficient to form a substantially homogeneous preceramic resinformulation (e.g., the polycarbosilane preceramic polymer, organicallymodified silicon dioxide preceramic polymer, and crosslinking agent maybe uniformly dispersed throughout the preceramic resin formulation), ormay be heterogeneous (e.g., at least one of the polycarbosilanepreceramic polymer, organically modified silicon dioxide preceramicpolymer, and crosslinking agent may be non-uniformly dispersedthroughout the preceramic resin formulation). In some embodiments, thepreceramic resin formulation is substantially homogeneous as formed.Organic solvents may, optionally, be used to form the preceramic resinformulation. During mixing, the preceramic resin formulation may bemaintained at a temperature below the lowest cure temperature of each ofthe components. In one embodiment, the polycarbosilane preceramicpolymer, organically modified silicon dioxide preceramic polymer, andcrosslinking agent are maintained at room temperature (from about 20° C.to about 25° C.) during mixing. A water-cooled jacket may be used, asneeded, to maintain the preceramic resin formulation at or near roomtemperature to inhibit potential reactions from occurring during themixing.

The preceramic resin formulation may exhibit a viscosity within a rangeof from about 200 cP at about 25° C. to about 5,500 cP at a temperatureof about 25° C., such as from about 800 cP at about 25° C. to about5,000 cP at a temperature of about 25° C. or from about 1,000 cP atabout 25° C. to about 5,000 cP at a temperature of about 25° C.

The preceramic resin formulation may be formed (e.g., fabricated) into adesired configuration or shape depending on the intended use of theceramic material. By way of example only, the preceramic resinformulation may be formed into a desired shape by coating, casting intoa mold, dispensing from a container onto a surface as an adhesive orsealant, hand placement (lay up), molding, such as vacuum bag molding orresin transfer molding, filament winding, such as wet filament winding,another suitable process, or combinations thereof. Once formed into thedesired shape, the preceramic resin formulation is cured (e.g.,crosslinked) to form a cured preceramic resin formulation and ceramified(e.g., pyrolyzed) to form the ceramic material. The conditions used tocure the preceramic resin formulation may be selected depending on thespecific polycarbosilane preceramic polymer and organically modifiedsilicon dioxide preceramic polymer present in the preceramic resinformulation. The cure temperature of the preceramic resin formulationmay range from about 0° C. (about 32° F.) to about 400° C. (about 752°F.), such as from about 20° C. to about 371° C. or from about 20° C. toabout 121° C. (about 250° F.). Depending on the cure temperature, thepreceramic resin formulation may be cured in an amount of time rangingfrom a few seconds (e.g., photoinitiated cure) to a few days. Byincreasing the cure temperature, a shorter amount of time may be neededto cure the preceramic resin formulation. Conversely, by decreasing thecure temperature, a longer amount of time may be needed to cure thepreceramic resin formulation. The curing of the preceramic resinformulation may be conducted using conventional processing equipment,which is not described in detail herein. During curing, thepolycarbosilane preceramic polymer and organically modified silicondioxide preceramic polymer in the preceramic resin formulation react(e.g., crosslink), forming a hardened material (i.e., the curedpreceramic resin formulation). Thus, the cured preceramic resinformulation includes a reaction product of the polycarbosilanepreceramic polymer and the organically modified silicon dioxidepreceramic polymer. By way of example only, the vinyl groups of thepreceramic resin formulation react with silicon-hydrogen bonds duringthe cure.

The cured preceramic resin formulation is ceramified to further hardenthe cured preceramic resin formulation and convert the cured preceramicresin formulation into the ceramic material. Thus, the ceramic materialincludes a reaction product of the polycarbosilane preceramic polymerand the organically modified silicon dioxide preceramic polymer. Thecured preceramic resin formulation may be exposed to a temperature ofgreater than about 649° C. (greater than about 1,200° F.), such as atemperature of greater than about 816° C. (greater than about 1,500° F.)or greater than about 1,093° C. (greater than about 2,000° F.). Theceramic yield of the ceramic material may be greater than about 50%,such as greater than about 70%, greater than about 75%, or greater thanabout 80% when ceramified at these temperatures. Without being bound byany theory, it is believed that the high degree of quaternary coordinateoxygen in the organically modified silicon dioxide preceramic polymerresults in the high ceramic yield. When silicon atoms are fullycoordinated with oxygen atoms, SiO₂ is maintained during the cure andceramification. The organically modified silicon dioxide preceramicpolymer has sufficient organic groups bonded to the silicon atoms tokeep the preceramic resin formulation in a polymeric state, whichenables ease of blending with other materials. It is also believed thatat a temperature of about 1,093° C. (about 2,000° F.), the preceramicresin formulation may be characterized as a semi-amorphoussilicon-oxy-carbide material.

With its heat resistance and reduced cracking, the ceramic materialformed from the preceramic resin formulation may be used in a variety ofarticles, such as in aerospace or other industries. The ceramic materialaccording to embodiments of the disclosure may be used to formcomponents of rocket motors or other aerostructures. The ceramicmaterial according to embodiments of the disclosure may be used as astructural component of a rocket motor or of a high temperatureaerostructure. The ceramic material may be used as a component of anozzle of the rocket motor or of a casing of the rocket motor. Theaerostructure may include, but is not limited to, a turbine, a turbineblade, a turbine housing, a turbine engine vane, an insulating tile, arotor blade, an insulation blanket, a compressor blade, a wingcomponent, a fuselage skin, a landing gear, an exhaust nozzle, an engineexhaust duct, a nose cone, a re-entry shield, or a heat shield. Inaddition to structural components, the ceramic material may be used asan oxidative resistant coating on a rocket motor nozzle or other hightemperature aerostructure, a high temperature adhesive, a mortarmaterial for filling cracks or gaps, an insulation, a thermal protectionmaterial, a thermal ablation material, or a matrix material of a ceramicmatrix composite (CMC). The ceramic material according to embodiments ofthe disclosure may also be used as a bonding material between othercomponents, such as between other components of a rocket motor or othercomponents of an aerostructure. The ceramic material may, therefore, bepart of a laminate structure that includes aerostructure components orrocket motor components.

FIG. 1 is a simplified cross-sectional view of a rocket motor 1000(e.g., a solid rocket motor), in accordance with embodiments of thedisclosure. The rocket motor 1000 may, for example, be configured to bea component (e.g., stage) of a larger assembly (e.g., a multi-stagerocket motor assembly). As shown in FIG. 1, the rocket motor 1000includes a casing 1002, a propellant structure 1004 disposed within thecasing 1002, and a nozzle assembly 1006 connected to an aft end of thecasing 1002. The rocket motor 1000 may also include one or more of aliner structure 1008 and an insulation structure 1010 between thepropellant structure 1004 and the casing 1002. For example, the linerstructure 1008 may be located on or over the propellant structure 1004,and the insulation structure 1010 may be located on and between theliner structure 1008 and an inner surface of the casing 1002. Thecomponents of the rocket motor 1000 may be formed using conventionalprocesses and equipment, which are not described in detail herein. Theceramic material according to embodiments of the disclosure may be usedin one or more components of the rocket motor 1000. By way of exampleonly, at least a portion of the nozzle assembly 1006 or the casing 1002may be formed of the ceramic material according to embodiments of thedisclosure.

While embodiments described herein refer to preceramic precursors ofsilicon carbide and silicon dioxide, the preceramic precursor of silicondioxide may also be used with preceramic precursors of other ceramics,such as preceramic precursors of silicon carbide, preceramic precursorsof silicon nitride, preceramic precursors of silicon hexaboride,preceramic precursors of aluminum nitride, preceramic precursors ofboron nitride, preceramic precursors of boron carbide, preceramicprecursors of titanium boride, preceramic precursors of titaniumcarbide, and preceramic precursors of hafnium carbide.

The following examples serve to explain embodiments of the disclosure inmore detail. These examples are not to be construed as being exhaustiveor exclusive as to the scope of this disclosure.

EXAMPLES Example 1 Precursor Resin Formulation

A preceramic resin formulation including 100 parts of a polycarbosilanepreceramic polymer commercially available from EEMS, LLC as CSO-110, 25parts of a organically modified silicon dioxide preceramic polymercommercially available from Gelest, Inc. as VQM-246, and 1 part of aplatinum catalyst commercially available from EEMS as CLC-PL005 wasprepared. The CSO-110, VQM-246, and platinum catalyst were combined toproduce the preceramic resin formulation including 80 wt % CSO-110 and20 wt % of the VQM-246. A control formulation including only CSO-110 wasalso produced.

The preceramic resin formulation and the control formulation wereexposed to 121° C. (250° F.) for 4 hours to cure the preceramic resinformulation and the control formulation, and then ceramified at atemperature of about 900° C. for 2 hours to produce the respectiveceramic materials. A post-cure after the 121° C. (250° F.) cure wasperformed at 370° C. (700° F.) for an additional 4 hours.

Example 2 Ceramic Yield and Mechanical Integrity

Thermogravimetric analysis (TGA) of the ceramic material formed from thepreceramic resin formulation of Example 1 and the ceramified controlformulation was conducted to determine the weight loss of the ceramicmaterials as a function of temperature. The TGA was conducted byconventional techniques. As shown in FIG. 2, the ceramic material formedfrom the preceramic resin formulation of Example 1 exhibited a 78.4%ceramic yield, while the ceramic material formed from the controlformulation exhibited a 64.6% ceramic yield. Therefore, the ceramicmaterial formed from the preceramic resin formulation of Example 1 had a21.4% increase in mass retention compared to the ceramified controlformulation including only the CSO-110. Thus, the ceramic yield of theceramic material formed from the preceramic resin formulation of Example1 was significantly increased compared to the ceramified controlformulation.

In addition to the increased ceramic yield, no cracking was observedwith the cured preceramic resin formulation (cured at 250° F. for 4hours) of Example 1, as shown in FIG. 3. The cured preceramic resinformulation formed from the polycarbosilane preceramic polymer and theorganically modified silicon dioxide preceramic polymer exhibited netshape curing with no cracking. In contrast, the cured controlformulation (cured at 250° F. for 4 hours) exhibited extensive cracking.

While the disclosure is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, the disclosure is not intended to be limited to the particularforms disclosed. Rather, the disclosure encompasses all modifications,equivalents, and alternatives falling within the scope of the disclosureas defined by the following appended claims and their legal equivalents.

What is claimed is:
 1. A preceramic resin formulation comprising apolycarbosilane preceramic polymer and an organically modified silicondioxide preceramic polymer.
 2. The preceramic resin formulation of claim1, wherein a viscosity of the polycarbosilane preceramic polymer is lessthan or equal to about 250 cP at a temperature of about 25° C. and aviscosity of the organically modified silicon dioxide preceramic polymeris greater than or equal to about 2,500 cP at a temperature of about 25°C.
 3. The preceramic resin formulation of claim 1, wherein thepolycarbosilane preceramic polymer comprises monomers having thechemical structure of

where R₁ and R₂ of each monomer is independently a hydrogen (H) group, amethyl (CH₃) group, a vinyl group (CH₂═CH) directly bonded to thesilicon atom, or a vinyl group (CH₂═CH) bonded to the silicon atom by analkyl linker, and n is an integer from 2 to 10,000.
 4. The preceramicresin formulation of claim 1, wherein the polycarbosilane preceramicpolymer is formulated to exhibit a viscosity of from about 40 cP toabout 120 cP at about 25° C.
 5. The preceramic resin formulation ofclaim 1, wherein the polycarbosilane preceramic polymer is formulated toexhibit a viscosity of from about 40 cP to about 100 cP at about 25° C.6. The preceramic resin formulation of claim 1, wherein the organicallymodified silicon dioxide preceramic polymer comprises monomers havingthe chemical structure of

where each of R₃ and R₄ is independently a methyl (CH₃) group, a vinylgroup (CH₂═CH) directly bonded to the silicon atom, or a vinyl group(CH₂═CH) bonded to the silicon atom by an alkyl linker, and n is aninteger from 2 to 10,000.
 7. The preceramic resin formulation of claim1, wherein the organically modified silicon dioxide preceramic polymeris formulated to exhibit a viscosity of from about 50,000 cP at 25° C.to about 60,000 cP at 25° C.
 8. The preceramic resin formulation ofclaim 1, wherein the organically modified silicon dioxide preceramicpolymer is formulated to exhibit a viscosity of from about 4,500 cP at25° C. to about 7,000 cP at 25° C.
 9. The preceramic resin formulationof claim 1, wherein the polycarbosilane preceramic polymer comprisesfrom about 10% by weight to about 90% by weight of the preceramic resinformulation.
 10. The preceramic resin formulation of claim 1, whereinthe organically modified silicon dioxide preceramic polymer comprisesfrom about 10% by weight to about 90% by weight of the preceramic resinformulation.
 11. The preceramic resin formulation of claim 1, furthercomprising a crosslinking agent.
 12. The preceramic resin formulation ofclaim 1, wherein the preceramic resin formulation is formulated toexhibit a viscosity of from about 1,000 cP at about 25° C. to about5,000 cP at about 25° C.
 13. A ceramic material comprising a reactionproduct of a polycarbosilane preceramic polymer and an organicallymodified silicon dioxide preceramic polymer.
 14. The ceramic material ofclaim 13, wherein the ceramic material is configured as at least aportion of a rocket motor nozzle or a rocket motor casing.
 15. Theceramic material of claim 13, wherein the ceramic material is configuredas at least a portion of a turbine, a turbine blade, a turbine housing,a turbine engine vane, an insulating tile, a rotor blade, an insulationblanket, a compressor blade, a wing component, a fuselage skin, alanding gear, an exhaust nozzle, an engine exhaust duct, a nose cone, are-entry shield, or a heat shield.
 16. The ceramic material of claim 13,wherein the ceramic material comprises an oxidative resistant coating ona rocket motor nozzle or other high temperature aerostructure, a hightemperature adhesive, a mortar material, an insulation, a thermalprotection material, a thermal ablation material, or a matrix materialof a ceramic matrix composite.
 17. A method of forming a preceramicresin formulation, comprising: combining a polycarbosilane preceramicpolymer and an organically modified silicon dioxide preceramic polymerwith a crosslinking agent.
 18. A method of forming a ceramic material,comprising: forming a preceramic resin formulation comprising apolycarbosilane preceramic polymer, an organically modified silicondioxide preceramic polymer, and a crosslinking agent; curing thepreceramic resin formulation to form a cured preceramic resinformulation; and ceramifying the cured preceramic resin formulation toform a ceramic material.
 19. The method of claim 18, wherein curing thepreceramic resin formulation to form a cured preceramic resinformulation comprises reacting vinyl groups of the polycarbosilanepreceramic polymer with silicon-hydrogen bonds of the organicallymodified silicon dioxide preceramic polymer.
 20. The method of claim 18,wherein curing the preceramic resin formulation to form a curedpreceramic resin formulation comprises exposing the preceramic resinformulation to a temperature of from about 0° C. to about 400° C. 21.The method of claim 18, wherein ceramifying the cured preceramic resinformulation to form a ceramic material comprises forming the ceramicmaterial at a ceramic yield of greater than about 70%.
 22. The method ofclaim 18, further comprising forming the preceramic resin formulationinto a shape before curing the preceramic resin formulation.
 23. Themethod of claim 22, wherein forming the preceramic resin formulationinto a shape before curing the preceramic resin formulation comprisesforming the preceramic resin formulation into a component of a rocketmotor nozzle before curing.
 24. The method of claim 22, wherein formingthe preceramic resin formulation into a shape before curing thepreceramic resin formulation comprises forming the preceramic resinformulation into a turbine or a heat shield before curing.
 25. Anarticle, comprising: a reaction product of a polycarbosilane preceramicpolymer and an organically modified silicon dioxide preceramic polymer,the article configured as a component of a rocket motor or of a hightemperature aerostructure.
 26. The article of claim 25, wherein thearticle comprises at least a portion of a rocket motor nozzle or arocket motor casing.
 27. The article of claim 25, wherein the articlecomprises at least a portion of a turbine, a turbine blade, a turbinehousing, a turbine engine vane, an insulating tile, a rotor blade, aninsulation blanket, a compressor blade, a wing component, a fuselageskin, a landing gear, an exhaust nozzle, an engine exhaust duct, a nosecone, a re-entry shield, a laminate structure, or a heat shield.
 28. Thearticle of claim 25, wherein the article comprises an oxidativeresistant coating on a rocket motor nozzle or other high temperatureaerostructure, a high temperature adhesive, a mortar material, aninsulation, a thermal protection material, a thermal ablation material,or a matrix material of a ceramic matrix composite.